The present invention relates to a video processing apparatus and method and, more particularly, to such apparatus and method for use with an electronic still camera for recording and/or reproducing still image digital video signals in a compressed form onto and/or from a recording medium such as an optical disk, a magneto-optical disk or a semiconductor memory.
In a digital recording and/or reproducing type electronic still camera, an image of an object may be supplied through a photographing or charge coupled device (CCD) so as to obtain a video signal. Such video signal may be converted to digital form and compressed in accordance with an image compression technique of the Joint Photographic Experts Group (JPEG) which may utilize a discrete cosine transform (DCT) and variable-length coding. As a result of such JPEG technique, colored still image data may be compressed with a relatively high compression ratio, such as 1 to 1/100. The digital compressed video signal may thereafter be recorded on a recording medium, such as a magneto-optical disk.
The above-described electronic still camera which records data in a digital form onto a magneto-optical disk has numerous advantages. For example, a relatively large number of still image data may be recorded on one disk, the quality of the recorded images may remain substantially high and may not substantially deteriorate over time, compilation of data is relatively easy, and still image data may be copied into a computer. Furthermore, such use is believed to increase in the future.
A user or operator of the digital type electronic still cameras may wish to extract and display only a part of an original image. Additionally, the user may wish to enlarge or reduce a part of an original image, modify it, move or rotate it and so forth. To perform these latter functions, such part of the original image is extracted. Moreover, a part of an original image may be extracted in numerous other situations. For example, consider the situation wherein an original image is read or introduced through a scanner. In such situation, the image may be larger than a display plane and, as such, a part of the original image is cut so as to display the original image in the display plane. However, to perform such extraction of a part of an original image may necessitate processing of the image data and the use of multiple memories as hereinbelow described.
More specifically, since digital type electronic still cameras may record/reproduce still image data which is compressed in accordance with a JPEG technique, a desired area of an original image to be extracted or cut out may not be designated directly from the JPEG-compressed data. Instead, the desired area is designated or extracted from the original image in a non-compressed form. Accordingly, to extract a desired area from JPEG-compressed data, the original image is reconstructed from the JPEG-compressed data and processing pertaining to the extraction of the designated area is performed. That is, all of the data of a field of the JPEG-compressed data is expanded into the original image data, the expanded data (original image) is stored in a memory, a corresponding area on memory is designated, the desired part of the original image is cut out or extracted, and such part is stored in an image memory.
An example of the above extraction procedure is illustrated in FIGS. 9A-9D. That is, as shown in FIG. 9A, JPEG-compressed data is expanded so as to form an original image which is stored in a memory. A read address corresponding to a region A1 is designated from the original image in the memory, and the image of the region A1 is read out. The data in the region A1 is written in an image memory as shown in FIG. 9B. Upon performing a data interpolation or thinning operation or the like, an enlarged or reduced image may be formed as respectively illustrated in FIGS. 9C and 9D and written into the image memory.
The above-described technique, which expands JPEG-compressed data into original image data, stores it in a memory, cuts out a desired part of the original image in a designated area of the memory, and stores it in an image memory, utilizes an additional memory for temporarily storing the original image data expanded from the JPEG-compressed data. As a result, the number of components in a circuit utilized to perform such technique, and/or the complexity thereof, and/or cost thereof may be relatively high.